Visual evoked potentials (VEPs) can provide important diagnostic information regarding the functional integrity of the visual system. This document updates the ISCEV standard for clinical VEP testing and supersedes the 2009 standard. The main changes in this revision are the acknowledgment that pattern stimuli can be produced using a variety of technologies with an emphasis on the need for manufacturers to ensure that there is no luminance change during pattern reversal or pattern onset/offset. The document is also edited to bring the VEP standard into closer harmony with other ISCEV standards. The ISCEV standard VEP is based on a subset of stimulus and recording conditions that provide core clinical information and can be performed by most clinical electrophysiology laboratories throughout the world. These are: (1) Pattern-reversal VEPs elicited by checkerboard stimuli with large 1 degree (°) and small 0.25° checks. (2) Pattern onset/offset VEPs elicited by checkerboard stimuli with large 1° and small 0.25° checks. (3) Flash VEPs elicited by a flash (brief luminance increment) which subtends a visual field of at least 20°. The ISCEV standard VEP protocols are defined for a single recording channel with a midline occipital active electrode. These protocols are intended for assessment of the eye and/or optic nerves anterior to the optic chiasm. Extended, multi-channel protocols are required to evaluate postchiasmal lesions.

Visual evoked potentials (VEPs) can provide important diagnostic information regarding the functional integrity of the visual system. This document updates the ISCEV standard for clinical VEP testing and supersedes the 2004 standard. The major change in this revision is that test parameters have been made more precise to achieve better consistency of results within and between test centers. The ISCEV standard VEP protocols are defined for a single recording channel with a midline occipital active electrode. These protocols are intended for assessment of prechiasmal function; additional electrode sites are recommended for evaluation of chiasmal and postchiasmal function. ISCEV has selected a subset of stimulus and recording conditions that provide core clinical information and can be performed by most clinical electrophysiology laboratories throughout the world. These are: 1. Pattern-reversal VEPs elicited by checkerboard stimuli with large 1°(i.e., 60 min of arc; min) and small 0.25° (15 min In memory of Vaegan (1943Vaegan ( -2009: friend, dedicated ISCEV member, and member of this VEP standardization committee.

This document presents the current (2004) standard\ud for the visual evoked potential (VEP). The VEP\ud is an evoked electrophysiological potential that can\ud be extracted, using signal averaging, from the electroencephalographic\ud activity recorded at the scalp. The\ud VEP can provide important diagnostic information\ud regarding the functional integrity of the visual system.\ud The current standard presents basic responses\ud elicited by three commonly used stimulus conditions\ud using a single, midline recording channel with\ud an occipital, active electrode. Because chiasmal and\ud retrochiasmal diseases may be missed using a single\ud channel, three channels using the midline and two\ud lateral active electrodes are suggested when one goes\ud beyond the standard and tests patients for chiasmal\ud and retrochiasmal dysfunction.\ud Pattern reversal is the preferred technique for most\ud clinical purposes. The results of pattern reversal\ud stimuli are less variable in waveform and timing\ud than the results elicited by other stimuli. The pattern\ud onset/offset technique can be useful in the detection of\ud malingering and in patients with nystagmus, and the\ud flash VEP is particularly useful when optical factors\ud or poor cooperation make the use of pattern stimulation\ud inappropriate. The intent of this standard is that\ud at least one of these techniques should be included\ud in every clinical VEP recording session so that all\ud laboratories will have a common core of information\ud that can be shared or compared

Clinical electrophysiological testing of the visual system incorporates a range of noninvasive tests and provides an objective indication of function relating to different locations and cell types within the visual system. This document developed by the International Society for Clinical Electrophysiology of Vision provides an introduction to standard visual electrodiagnostic procedures in widespread use including the full-field electroretinogram (ERG), the pattern electroretinogram (pattern ERG or PERG), the multifocal electroretinogram (multifocal ERG or mfERG), the electrooculogram (EOG) and the cortical-derived visual evoked potential (VEP). The guideline outlines the basic principles of testing. Common clinical presentations and symptoms are described with illustrative examples and suggested investigation strategies.

P>Ocular manifestations are very common in all types of mucopolysaccharidoses (MPS) and often lead to visual impairment. They arise as a result of the accumulation of glycosaminoglycans deposits in ocular tissues or secondary to increased intracranial pressure. Typical ocular features in MPS include corneal clouding, retinopathy, glaucoma, optic disc swelling, optic atrophy, and ocular motility and refractive error problems. This paper reviews the ocular features in patients with MPS, discusses the diagnosis of these ocular features and the diagnostic problems that may arise in patients (children) with MPS, and highlights the central role ophthalmologists may play in the diagnosis and follow-up of these patients